二叉树高度

def solve():
    class TreeNode:
        def __init__(self, val):
            self.val = val
            self.left = None
            self.right = None
    root = TreeNode(1)
    root.left = TreeNode(2)
    root.right = TreeNode(3)
    root.left.left = TreeNode(4)
    root.left.right = TreeNode(5)
    def height(node):
        if node is None:
            return 0
        return 1 + max(height(node.left), height(node.right))
    print(height(root))

solve()